The government is promising "the most significant single reform of social care law for 60 years" after the Law Commission published its final proposals for modernisation and rationalisation of legislation governing care and support for older and disabled people, those with mental health problems and carers.

Charities and user groups broadly welcomed the proposals as a singular opportunity to sort out what one called the "dog's breakfast" of statutes and guidance dating back to 1948 and appearing incomprehensible to most non-lawyers.

In addition to simplifying more than 40 existing statutes and thousands of pages of guidance, the Law Commission's plans for England and Wales would entitle carers to an assessment of their support needs irrespective of how intensively they provide care, place a duty on councils to investigate abuse and neglect of adults, allow direct payments to be used to fund residential care and improve "portability" of entitlement to care and support services if people move from one council area to another.

Frances Patterson QC, the public law commissioner who led the three-year project to review existing law, said: "Our recommendations will bring much-needed clarity and accessibility to this important area of the law and have a major, beneficial impact on the lives of many of our most vulnerable citizens."

The government has indicated it will incorporate the commission's proposals in a care and support white paper, expected in December, together with the outcome of the Dilnot review of the funding of long-term care. Legislation could follow next year.

Paul Burstow, the care services minister, said the Law Commission's final report provided "a strong foundation" for the most significant reform of social care law for 60 years, suggesting the government might not adopt the 76 recommendations in their entirety.

The report shows that the commission has refined its previous, consultative proposals, which some critics felt did not adequately address the development of personalisation and self-directed care. The commission has also introduced an overarching principle of promotion of wellbeing and has provided for separate statutes for England and Wales.

Lord Justice Munby, chairman of the commission, said: "What we are trying to do is create a legal framework into which governments can, from time to time, slot different policies."

The older people's charity Age UK strongly welcomed the proposals as a solution to the current "complicated mess".

Michelle Mitchell, Age UK's charity director, said: "The Law Commission's recommendations provide a one-off opportunity to replace this dog's breakfast with a clear, logical and consistent framework. It is important, as we move forward to actual legislation, that political wrangling does not result in this clarity being lost."

Gary FitzGerald, chief executive of Action on Elder Abuse, applauded the proposed duty on councils to investigate abuse and neglect. He said: "Too many older and other vulnerable adults are relying on a postcode lottery for their protection and these recommendations will finally bring this situation to an end."

In Control, the social enterprise which promotes self-directed care, gave the proposals a general welcome but said they still did not go far enough in some key respects and could actually hinder further development of personalisation by defining a limited list of "community care services" from which people would choose.

"Overall the plans are positive but fall just short of the radical overhaul that we would have liked to have seen," said Andrew Tyson, In Control's policy lead.

User groups are certain to press the government to allow full portability of entitlement to care and support services. Under the commission's blueprint, continuity would be guaranteed only until the individual's needs were reassessed by the council to which they had moved.